import sys
input = sys.stdin.readline

T=int(input())
for t in range(T):
    x = input().strip()
    y = input().strip()
    xy = x+y
    yx = y+x
    if xy > yx:
        print("X")
    elif xy < yx:
        print("Y")
    else:
        print("X" if len(x)>len(y) else "Y")